Heinrich Hertz


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Heinrich Hertz
Autograph of Heinrich Hertz.png

Heinrich Rudolf Hertz (born February 22, 1857 in Hamburg , † January 1, 1894 in Bonn ) was a German physicist . In 1886 he was the first to generate and detect electromagnetic waves in experiments and is therefore considered to be the discoverer. In his honor, the international unit for frequency was called Hertz (abbreviated to the unit symbol Hz ).

Life

origin

Heinrich Rudolf Hertz came from a respected Hanseatic family. His father Gustav Ferdinand Hertz (original name David Gustav Hertz, 1827–1914) came from a Jewish family, but converted to Christianity. He had a doctorate in law, a judge from 1877 and a senator and president of the Hamburg judicial administration from 1887 to 1904 . The mother Anna Elisabeth b. Pfefferkorn was the daughter of a garrison doctor.

Heinrich Hertz had four siblings, the brothers Gustav Theodor (* 1858), Rudolf (* 1861) and Otto (* 1867) as well as the sister Melanie (* 1873). The brother Gustav Theodor Hertz was the father of Nobel Prize winner Gustav Ludwig Hertz and the grandfather of the atomic physicist and information scientist Hardwin Jungclaussen .

In 1886 Heinrich Hertz married Elisabeth Doll (1864–1941). The marriage resulted in two daughters, Johanna (1887–1967) and Mathilde (1891–1975).

Training and teaching

Hertz did his Abitur at the Johanneum in Hamburg and then prepared for an engineering degree in a design office in Frankfurt am Main . He broke off his studies in Dresden after the first semester because only the mathematics lectures there could inspire him. After a year of military service, he began to study mathematics and physics at the Technical University of Munich .

In 1878 he moved to the Berlin Friedrich Wilhelms University . He received his doctorate at the age of 23 with a thesis on the rotation of metal balls in a magnetic field and stayed for two years as a research and lecture assistant at Hermann von Helmholtz in Berlin, where he began to investigate the physical nature of cathode rays.

In 1883, Hertz became a private lecturer for theoretical physics at the Christian Albrechts University in Kiel . From 1885 to 1889 he taught as a professor of physics at the Technical University of Karlsruhe .

From 1889 he was professor of physics at the Rheinische Friedrich-Wilhelms-Universität Bonn , after rejecting appointments to Berlin, Giessen and America.

Act

Such a spark inductor developed by Heinrich Daniel Rühmkorff served Hertz as a generator in his spark experiments
Hertzian experimental set-up with a spark inductor and a dipole transmitting antenna that is capacitively extended by spheres and an interrupted metal ring as a receiving antenna

In 1886, Hertz was the first to succeed in experimentally generating and demonstrating free electromagnetic waves (in the ultra-short wave range at a frequency of around 80  MHz ). On November 13, 1886, he succeeded in an experiment in generating electromagnetic waves and transmitting them from a transmitter to a receiver. With this he confirmed the basic equations of electromagnetism developed by James Clerk Maxwell and in particular the electromagnetic theory of light . The electromagnetic radiation of an oscillating electrical dipole, which Hertz proved, corresponded exactly to the one he himself had calculated beforehand from these equations for a point-shaped dipole (see Hertz oscillator ).

Heinrich Hertz was working in Karlsruhe at the time and continued his research into invisible electromagnetic waves (radio waves). He demonstrated that they propagate in the same way and at the same speed as light waves (see refraction , polarization and reflection ). At the Berlin Academy of Sciences he taught on December 13, 1888 in his research report "About Radiation of Electric Force" on electromagnetic waves. Heinrich Hertz's results provided the basis for the development of wireless telegraphy and radio .

In 1886, Hertz investigated the external photoelectric effect discovered by Alexandre Edmond Becquerel in 1839 . This investigation was continued a year later by his assistant Wilhelm Hallwachs ( Hallwax effect ). The effect played a special role in the formulation of the light quantum hypothesis by Albert Einstein in 1905.

Using the theory of elasticity, Hertz calculated the stresses at pressure contact between curved surfaces ( Hertzian pressure ).

As a Bonn professor from 1889, he continued the investigations into the nature of cathode rays that had already begun in Berlin and, in his last experimental study in 1891, showed that they can penetrate thin metal foils. His assistant Philipp Lenard later expanded this experiment, using a metal sieve with an aluminum foil instead of the thin foil. Cathode rays from the vacuum tube could escape into the air through this “Lenard window”. "For his work on cathode rays" Lenard then received the Nobel Prize in Physics in 1905.

death

Grave in the Ohlsdorf cemetery

In 1892, after a severe migraine attack, Hertz was diagnosed with Wegener's granulomatosis , and in 1894 he died of it in Bonn. He is buried in the Ohlsdorf cemetery in Hamburg. His wife Elisabeth did not remarry. The two daughters did not marry either and had no offspring.

time of the nationalsocialism

Heinrich Hertz never defined himself as a Jew and was Lutheran all his life, as his father's family had converted to Evangelical Lutheran Christianity. The name Hertz, a common name among German Jews, did not mean that as a physicist he was exposed to anti-Semitic prejudices. It was only during the Nazi era that people posthumously distanced themselves from the successful scientist , who in the racist jargon of National Socialism was called a “ half-Jew ”. Because of his Jewish descent, his portrait was removed from Hamburg City Hall, and institutions and streets named after him were mostly renamed. There were also considerations to rename the Hertz unit named after him , which had been introduced internationally in 1933, while retaining the abbreviation “Hz” in “Helmholtz”.

His daughter, the biologist Mathilde Hertz , and his nephew, the Nobel laureate in physics, Gustav Hertz, were removed from the public service under the law to restore the civil service. Mathilde Hertz emigrated to England in 1935, where her mother and sister followed in 1936.

Honors

Aether wave , monument to Heinrich Hertz in Hamburg's Eichenpark

medal

Monuments

  • A portrait relief on one of the pillars of honor in the town hall hall, which has been in Hamburg's town hall since 1897 , was removed by the National Socialists, but restored after the war.
  • In 1933 the installation of a bronze sculpture "Aether Wave" commissioned by the Hamburg Senate in honor of Hertz was prevented. The forgotten sculpture by Friedrich Wield was only erected in 1994 in the oak park on the Alster. In 2016, the sculpture was moved within the Harvestehude district to the place on the grounds of the NDR broadcasting house, which was already favored in the 1930s.

Heinrich Hertz as namesake

Bust on the south campus of the Karlsruhe Institute of Technology

The following were named after Hertz:

Fonts (selection)

About induction in rotating spheres
(Berlin, 1880)
  • About induction in rotating spheres . Inaugural dissertation Berlin, 1880.
  • About the contact of solid elastic bodies , Journal for pure and applied mathematics, Volume 92, 1881, pp. 156-171 ( PDF file ; 1.81 MB)
  • The constitution of matter. A lecture on the fundamentals of physics from 1884. Edited by Albrecht Fölsing, Berlin 1999.
  • About very rapid electrical oscillations. In: Annals of Physics. Volume 267, Number 7, 1887, pp. 421-448. ( PDF file ; 1.4 MB)
  • About the influence of ultraviolet light on the electrical discharge. In: Annals of Physics. Volume 267, Number 8, 1887, pp. 983-1000.
  • About the action of a straight electrical oscillation on an adjacent current path. In: Annals of Physics. Volume 270, Number 5, 1888, pp. 155-170.
  • About the speed of propagation of the electrodynamic effects. In: Annals of Physics. Volume 270, Number 7, 1888, pp. 551-569.
  • On the relationship between light and electricity. Lecture given at the 62nd meeting of German naturalists and doctors in Heidelberg. Emil Strauss, 1889.
  • Collected Works, Volume 2: Investigations into the Propagation of Electric Power , Barth 1894, Archives
  • The principles of mechanics presented in a new context , Leipzig, 1894, Archive

See also

literature

Web links

Commons : Heinrich Rudolf Hertz  - Collection of images, videos and audio files
Wikisource: Heinrich Hertz  - Sources and full texts

Individual evidence

  1. Buildings Integral to the Former Life and / or Persecution of Jews in Hamburg - Eimsbüttel / Rotherbaum I. ( Memento from August 4, 2009 in the Internet Archive )
  2. Hardwin Jungclaussen : Free in three dictatorships - How I experienced my life and how I found my happiness. Autobiography. trafo publishing group Dr. Wolfgang Weist, trafo Literaturverlag, Autobiographies Volume 48 series, Berlin 2015, ISBN 978-3-86465-050-5 .
  3. Jörg Willer: Didactics in the Third Reich using the example of physics. In: Medical historical messages. Journal for the history of science and specialist prose research. Volume 34, 2015 (2016), ISBN 978-3-86888-118-9 , pp. 105–121, here: p. 105.
  4. Heinrich Hertz's original apparatus in the Deutsches Museum , accessed on April 29, 2019.
  5. ^ Albrecht Fölsing : Heinrich Hertz. Hoffmann and Campe, Hamburg 1997, ISBN 3-455-11212-9 , p. 275.
  6. Andrea Westhoff: Discoverer of the waves . In: Deutschlandradio . February 22, 2007.
  7. Jörg Willer: Didactics in the Third Reich using the example of physics. In: Medical historical messages. Journal for the history of science and specialist prose research. Volume 34, 2015, ISBN 978-3-86888-118-9 , pp. 105–121, here: pp. 105 f.
  8. ^ Susskind, Charles. (1995). Heinrich Hertz: A Short Life. San Francisco: San Francisco Press. ISBN 0-911302-74-3
  9. Koertge, Noretta. (2007). Dictionary of Scientific Biography, Vol. 6, p. 340.
  10. a b c Stefan Wolff: Heinrich Hertz - Jews against their will . In: Jüdische Allgemeine . January 4, 2008 ( online ).
  11. Jörg Willer: Didactics in the Third Reich using the example of physics. In: Medical historical messages. Journal for the history of science and specialist prose research. Volume 34, 2015, ISBN 978-3-86888-118-9 , pp. 105–121, here: p. 106.
  12. Robertson, Struan: Hertz biography ( Memento from August 4, 2009 in the Internet Archive )
  13. ^ Jean-Marie Thiébaud: L'Ordre du Trésor sacré (Japon). In: Editions L'Harmattan. L'Harmattan, December 2007, accessed July 27, 2009 (French).
  14. Photos of Eichenpark and Hertzdenkmal on fotograf-hamburg.com
  15. Heinrich Hertz Monument Hamburg: Monument with a moving history. Retrieved December 27, 2016 .